WhatsApp is also really strong here in Germany and other parts of Europe. More of my friends are on WhatsApp than Facebook (only very few more though).
It has basically replaced texting. Even my mom use it, which for me it's the definition of "wildly popular".
So, WhatsApp is definitely used in high-profit markets as well.
Source: http://www.nu.nl/tech/3506473/whatsapp-heeft-kwart-miljard-a...
WhatsApp users are mostly not early adopters like you and your friends. They are ordinary people, because WhatsApp is is a simple communication tool targeted to everyone. And that's why they keep doubling their user base.